Bug in GAP installation provided by SageMath?

[Peter Mueller]

While `libgap.SimpleGroup("J2")` yields the expected result, `libgap.SimpleGroup("J3")` raises a `GAPError: Error, The AtlasRep package could not load a group with parameters [ "J3" ]`. Calling `libgap.LoadPackage("AtlasRep")` returns without errors, but the problem persists.

The same happens when starting GAP directly from a shell via `sage -gap` and calling `SimpleGroup("J3");`. It is not a GAP bug, for a a local installation of GAP (same version  4.12.2) just works fine.

I have this problem in Sage versions 9.8 and 10.0.beta6. The same failure on the SageMathCell too.

-- Peter Mueller

[Dima Pasechnik]

That's because by default Sage's installation of AtlasRep does not
fetch data from the internet: we patch
local/lib/gap/pkg/atlasrep/gap/userpref.g
so that it says
default:= false;

The reason is that our release manager runs build tests in an no internet mode,
and something breaks without this patch.

So you can either go and edit the file above, or use a proper GAP way
to override
AtlasRepAccessRemoteFiles from
https://www.math.rwth-aachen.de/~Thomas.Breuer/atlasrep/doc/chap4.html
(and let's know how to do this, please, if you figure this out)

HTH
Dima

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[Peter Mueller]

Thanks, the following line resolves the issue in Sage 10.0.beta6 (but not in 9.8, but I don't care):

`libgap.SetUserPreference("AtlasRep", "AtlasRepAccessRemoteFiles", true )`

Dima Pasechnik schrieb am Dienstag, 18. April 2023 um 12:50:49 UTC+2:

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